The present disclosure relates to proximity sensors. More specifically, the present disclosure relates to water delivery devices including proximity sensors.
Water delivery devices are known that include proximity sensors. One example proximity sensor is a position sensing detector (PSD) sensor which provides range information based on an angle of reflection from an infrared (IR) emitter to an analog detector. This sensor arrangement works well for sensing objects that produce diffuse return signals such as hands or plastic objects, but have difficulty with highly polished or smooth object such as metal or glass. Water can also affect distance reading accuracy.
Two primary issues with the sensing of shiny object or objects in water is that the distance reading have significant error or there is a large percentage of noise/instability in the readings. The main cause for instability in the range readings provided by a PSD sensor is its inherent averaging of the received signal. The range is determined by the position along the length of the sensor which receives the highest intensity of the transmitted IR light. In normal operation this will be at one extreme end for light reflected from a close object, and the other extreme end for light reflected from a distant object. In the case of a sink, features on a base of a shiny sink, or ripples in the water can cause additional, spurious reflections of the transmitted light. These spurious reflections are averaged with the desired signal and cause the PSD to produce an unreliable and unstable output.